Motor control.



W. P. JACKSON.

MOTOR CONTROL. APPLICATION FILED JUNE 18, 1912.

1,077,717. Patented Nomi, 1913.

/a v /3 /z WILLIAM. E JICK-SON, ami [Mums 5" respectively, which makecontact with "UNITED STATES PATENT 'onniou.

WILLIAM P. JACKSON, OF OAKLAND, CALIFORNIA.

Moron common.

To all whom it may concern:

Be it known that I, WVILLIAM P. J ACKSON,

a citizen of the United States, residing at Oakland, in the county ofAlameda and 5 State of California, have invented certain new and usefulImprovements in Motor Controls, of which the following is aspecification.

This invention relates to a system of speed control for direct currentseries motors, the principal object of which is to automatically controlthe field strength of suchmotor so that when accelerating and a certainpredetermined speed is reached the field strength will be automaticallyreduced thereby"-furJierincreasing the motor speed. Such a device isparticularly applicable to traction cars enabling increased speeds to beobtained without increasing the gear ratio and thereby increasing thepower consumption. This system vis applied by either shunting the seriesfield through a suitable "resistance or by short circuiting some of thefield which in either case reduces the .fi'eld strength. The manner inwhich these ob jects and results are accomplished will be understoodfrom the following specification and the accompanying drawing forming apart thereof. 80 In the-drawing, Figure 1 is a diagrammatical viewshowing the application of the system as arranged to short circuit turnsof the series-field. Fig.2 is a diagrammatical yiew showing theapplication using a shunt around "the series fiel 4 In the drawings 1denotes the armature of a seriesmotor and 2 the series field thereof. InFig. 1, solenoid controlled switches 3 and 4 are provided, to thearmatu-rcs of which are attached conducting strips 5 and terminals 6 and7 when the respective armatures are pulled'up. Terminals 7 and 7 areconnected by conductors 8 and 8 respectively with the coils of theseries field at a oint intermediate the length thereof. Terminal 6is.connected by conductor 9 or 9 with the end of the field Winding. Thecoils of switches 3 and 4am one terminal connected by conductor 10 or 10to one armature terminal of motor 1, the other end being connectedthrough conductor 11 or 11' tothe other armature terminal. Thus,

, arrnature terminals. Interposed in conduc- Specification of LettersPatent.

relays 3 and 4 will receive current in p nto. the impressed voltageacross the tors 11 and 11' are contacts 12 and 13 adapted to be-closedby the contact yoke 14 of relays 15 or 16, the windings of which areconnected directly in series and in series with the main current.Conductor 17 connects relay 16 with a controlling device 20 and thenceto a source of current as 21.

In the form shown in Fig. 2 the contacts of switches 3 are connectedthrough 8 and 9 to the terminals of the field coil 2, a suitableresistance 18 being placed in one of these conductors.

The operation of this system is as follows When the circuit is closedthrough the controller 20 or any other suitable type of manuallyoperated apparatus, current flows through conductors 17, relays 15 and16 to armature 1, and thence through the field coils 2 throughconductors 9' and 19 to the generator 21. Immediately on the closingofthis circuit, relays 15 and 16 pick up, opening the circuit throughswitches 3 and 4.. This condition holds during acceleration and when thecurrent begins to drop toward the end of the accelerating period relays16 and 15 allow their armature to fall, closing circuits throughswitches 3 and 4 respectively. Now, the current through these switcheswill be proportional to th'e counter electromotive force across thearmature terminals and hence to the armature speed. Thus switch 3 isadjusted to operate when the highest regular speed is reached to shortcircuit a number of turns of the ,field winding 2, thus decreasing thefield strength and thereby increasing the speed. This increase of speedisthen sufiicient to operate switch.

4 which closes a short circuit around a greater number of 0011s,. thusfurther increasing the speed. In the form shown in Having thus describedthe inventionla'l what is claimed as new, is 1. The combination. with agenerator and motor; of a wire connecting one pole of said motor and thegenerator, one portion of said wire forming the series field winding ofsaid motor, a solenoid having one end connected tosaid generator and theother end connected to the remaining pole of and mo- PatentedNov.4,1913.

Application filed June 1 1912- Serial 704,412" I i l l! I tor, a corefor said solenoid, a contact bar carried by said core, a pair ofcontacts engaged by said bar when the solenoid is de energized, a Wireconnecting one of said pair of contacts with the connection from thesolenoid to. the motor, a wire connecting the remaining contact of thepair with 'the first mentioned wire between the series field winding andthe armature of the motor, the last mentioned wire including a secondsolenoid, a core for thesecond solenoid, a con tact bar carried by thesecond core, a pair of contacts engaged by said bar when the secondsolenoid is energized, a wire leading from one of the second pair ofcontacts to a point on the first mentioned wire between the series fieldwinding and said generator, and a wire leading from the remaining contact of the second pair to one of the wires connected to the firstmentioned pole of the motor.

2. The combination with a generator and motor; of a wire connecting onepole of said motor and the generator, one portion of said wire formingthe series field winding: of said motor, a solenoid haying one endconnected to said generator and the other end connected to the remainingpole .noid, a contact bar caried by the second core, a pair of contactsengaged by said bar when the second solenoid is energized, a wireleading from one of the second pair of contacts to point on the firstmentioned wire between the series field windin and said generator, andincluding a re tanec, and a wire connecting the mniaining Contact of thesecond pair with the Wire eonnedin;- the'second solenoid and the motor.

In testimony whereof i aiiix my signature in presence of two witnesses.

E me: n

fiopies of this patent may be obtained for five cents each, byaddressing the Commissioner of Patents, Washington, D. E.

